A biometric sensor identifies a user by his physiological or behavioral characteristics, such as palm print, finger print, iris, and voice. Such characteristics are also referred to as biometric characteristics. After identification of the user, the biometric sensor authorizes the user to perform any requested action. For example, a palm print sensor may allow the user to enter restricted areas after authentication of physiological or behavioral characteristics of the user's palm. Biometric sensors are generally installed at various locations for ensuring security and access control management, such as in organizations for keeping track of employee's attendance and ensuring security of systems and networks, in personal devices for tracking proper usage, and in electronic commerce to prevent online frauds.
The biometric sensors are generally placed in a holder that supports the sensor. The holder may indicate a proper position to the user from where the biometric sensor can easily detect the biometric characteristics. For example, the holder may allow the user to place his palm in a field of view of the biometric sensor, so that the biometric sensor can easily capture an impression or an image of the palm.